1. Field of the Invention
The invention generally relates to apparatus for forming concrete panels with embedded glass block and more particularly relates to apparatus for fabricating such panels in a manner which enhances their ability to resist leaks, bear loads and be transported safely.
2. Description of the Related Art
The prior art is replete with methods and apparatus for fabricating concrete panels. Such panels are commonly used to construct buildings, facades, walkways, driveways, etc.
Also known are concrete panels which incorporate glass block in a variety of shapes. When shaped like a paving stone or used in a driveway or walkway the glass is often referred to as "paver block". Concrete panels with embedded glass block are used in virtually every application where ordinary concrete can be used and is decorative as well as functional. The glass embedded panels in some instances permit the passage of light through an otherwise opaque panel. In many instances the load bearing capacity of the glass embedded panels is important, for example, if a car or truck is to be driven over the panel or if the panel forms a load bearing portion of a structure.
One arrangement for securing glass in concrete is taught in U.S. Pat. No. 422,218, issued to J. Jacobs, entitled "Illuminating Tile", issued Feb. 25, 1890. The Jacobs patent is directed to increasing the amount of light that can be passed via illuminating tiles. According to the illustrative embodiment set forth by Jacobs the tiles form a walkway. To secure the tiles, Jacobs teaches setting an illuminating lens (the glass block) in an enclosing ring, made separate from a metal supporting plate upon which the ring rests. The ring is then locked in concrete which is poured into a form comprised of the metal plate. Jacobs then teaches waterproofing the tile via filling the space between the enclosing ring and the glass lens with brimstone, cement, or other waterproof packing, above a portion of the lens which is flush with the ring The entire combination of ring, lens and sealant are mounted on the separate metal plate to provide support for the combination.
The metallic form and base required by Jacobs to support the enclosing ring, sealant and lens combination is undesirable for modern day construction because it adds weight to the panels and cost to the fabrication process.
Since the time of Jacobs, monolithic concrete panel structures have been fabricated which eliminate the aforementioned metallic support base. The known monolithic panel fabrication techniques involve forming a concrete panel with voids substantially in the shape of the glass block. The glass block inserted into the voids is then bonded to the concrete and sealed via a cementitious sealant such as grout. This technique is currently in use independent of whether the panel is designed to transmit light via the glass block (lens) and independent of whether the glass embedded panel is to support a load.
Although the enclosing ring and separate metal support base taught by Jacobs are eliminated by the monolithic panel fabrication techniques, unless a substantial cement base sits below the glass block, the overall panel's ability to bear a load is sacrificed. With a transparent panel the problem of building in enough support for an anticipated load is compounded by the limited size of any concrete base upon which the lens can rest and still provide an opening for light.
In addition, the handling and transportation of panels with embedded glass block, particularly of the monolithic type, has proven to be problematic. The cementitious material commonly used to seal and waterproof such panels is typically inserted directly between the glass block and cement panel itself in the location where the Jacobs type retaining ring existed. Such sealing techniques have the effect of putting a rigid mass between the concrete and glass which very often cracks during handling and transportation. Still further, a cementitious sealant is pourous and with one face against concrete and the other against glass, the waterproofing characteristic of the seal is diminished.
Prior art techniques are also known which were devised to eliminate not only the rings and steel support plates, but also the cementitious seal. U.S. Pat. No. 2,426,796, issued Sept. 2, 1947 to F. F. Stadelhofer, entitled "Concrete Wall Form", teaches methods and apparatus to cast glass block directly into concrete to eliminate after-fitting, glazing and grouting. With virtually no cushioning of the glass block in the concrete, these panels are also susceptible to being damaged while being transported and the desired waterproof seal between the glass and concrete is nonexistent.
Based on the known techniques for fabricating concrete panels with embedded glass block, it is desirable to have panel fabricating apparatus which yield a glass embedded panel that does not require a metal support base, holds up well when being handled or transported, is waterproof and is capable of bearing desired, preselected loads. Such panel fabricating apparatus is desirable for forming both light transmitting and opaque concrete panels with embedded glass block.